How to Develop a Chat Server within an existing application

Hi,

There is a requirement in my Project (Windows Application) to generate Chat Server.

Requirement is Like,
Admin fires a Message from any Client machine, that message should be displayed to all the clients conneccted to my
SQL Server (Local Network as well as Internet) with in my application(May be a little form popup or any thing else) only.
Message is One way only, no requirement to Reply that message back. Just view message to all the connected client.

I am new to Network Programing Please, can any one guide me to develop such a facility in my application.